/*
VIM: let b:lcppflags="-std=c++11 -O2 -pthread"
VIM: let b:wcppflags="/O2 /EHsc /DWIN32"
VIM: let b:cppflags=g:Iboost.g:Itbb
VIM: let b:ldflags=g:Lboost.g:LtbbD
VIM: let b:ldlibpath=g:Bboost.g:Btbb
VIM: let b:argv=""
*/
#include <cstdio>
#include <iostream>
#include <exception>
#include <thread>
#include <chrono>

#include <tbb/task.h>

/*
 *  Conclusion:
 *      The first task_sheduler_init is configuring number of threads in
 *      the thread pool. If the task scheduler initialised implicitly then
 *      the number of threads is the number of cores. To ensure uncomment
 *      the commented line below.
 */

class ChildTask : public tbb::task
{
    tbb::task * execute()
    {
        std::printf( "ChildTask is running.\n" );
        return nullptr;
    }
};

class ContTask : public tbb::task
{
    tbb::task * execute()
    {
        std::printf( "ContTask is running.\n" );
        return nullptr;
    }
};

tbb::task * t;

struct RootTask : public tbb::task
{
    tbb::task * execute()
    {
        std::printf( "RootTask is running.\n" );

        auto& c = *new( allocate_continuation()) ContTask();
        t = &c;

        tbb::task& ctask1 = *new( c.allocate_child() ) ChildTask();
        tbb::task& ctask2 = *new( c.allocate_child() ) ChildTask();
        c.set_ref_count( 3 );
        spawn( ctask1 );
        spawn( ctask2 );


        std::printf( "RootTask is done.\n" );

        return nullptr;
    }
};


int main ( void )
{try{

    auto& rtask = *new( tbb::task::allocate_root()) RootTask();

    tbb::task::enqueue( rtask );

    std::this_thread::sleep_for( std::chrono::seconds(1) );
    std::printf( "After sleep.\n" );

    tbb::task::spawn( *new (t->allocate_child()) tbb::empty_task() );

    std::this_thread::sleep_for( std::chrono::seconds(1) );
    std::printf( "After second sleep.\n" );

    return 0;
}
catch ( const std::exception& e )
{
    std::cerr << std::endl
            << "std::exception(\"" << e.what() << "\")." << std::endl;
    return 2;
}
catch ( ... )
{
    std::cerr  << std::endl
            << "unknown exception." << std::endl;
    return 1;
}}